Objective—To develop an antibody that specifically recognizes collagenase-cleaved type-II collagen in equine articular cartilage.
Sample Population—Cartilage specimens from horses euthanatized for problems unrelated to the musculoskeletal system.
Procedure—A peptide was synthesized representing the carboxy- (C-) terminus (neoepitope) of the equine type-II collagen fragment created by mammalian collagenases. This peptide was used to produce a polyclonal antibody, characterized by western analysis for reactivity to native and collagenase-cleaved equine collagens. The antibody was evaluated as an antineoepitope antibody by ELISA, using peptides ± an amino acid at the C-terminus of the immunizing peptide. Collagen cleavage was assayed from equine articular cartilage cultured with interleukin-1 (IL-1), ± a synthetic MMP inhibitor, BAY 12-9566. Cartilage specimens from osteoarthritic and nonarthritic joints were compared for antibody staining.
Results—An antibody, 234CEQ, recognized only collagenase- generated 3/4-length fragments of equine type-II collagen. This was a true antineoepitope antibody, as altering the C-terminus of the immunizing peptide significantly decreased competition for binding in an inhibition ELISA. The IL-1-induced release of type-II collagen fragments from articular cartilage was prevented with the MMP inhibitor. Cartilage from an osteoarthritic joint of a horse had increased staining with the 234CEQ antibody, compared with normal articular cartilage.
Conclusions and Clinical Relevance—We generated an antineoepitope antibody recognizing collagenase- cleaved type-II collagen of horses. This antibody detects increases in type-II collagen cleavage in diseased equine articular cartilage. The 234CEQ antibody has the potential to aid in the early diagnosis of arthritis and to monitor treatment responses. (Am J Vet Res 2001;62:1031–1039)